Percussion attachment for portable drills



Nov. 22, 1955 2,724,573

A- E. LUNDQUIST PERCUSSION ATTACHMENT FOR PORTABLE DRILLS Filed July 26,1954 INVENTOR. AX EL E. LUNDQUIST ATTORNEY Axel E. Lundquist,UnityTownship,

Westmoreland County, Pa.

Application July 26, 1954, Serial No. 445,741 3 Claims. (Cl. 25541) Thisinvention relates to drills for penetrating .rock or masonry work and,in particular, to a device adapted to be used with a portable drill andeffective to impart successive impact blows to the shank of a drill asit is rotated continuously.

The object of the invention is to improve generally upon the device ofStrobel Patent No. 1,925,289, by providing an attachment which issimpler and cheaper to manufacture, more durable and efficient inoperation and capable of drilling a greater depth of hole beforereplacement of the drill becomes necessary.

In a preferredembodiment of the invention, I employ a driving barrelhaving a shank adapted to be engaged by the chuck of a conventionalportable drill. The bar rel is rotatable in one end of a holding sleeveand has endwise engagement with an anvil fixed therein, the contactingsurfaces of the barrel and anvil being toothed or notched to produce acontinuou s series of impact blows on relative rotation. A driven barrelrotatable in the other end of the sleeve has a shank extendingrearwardly through the anvil and a chuck or socket on the forward endfor receiving the shank of a drill. I provide means to insure rotationof the driven barrel withthe driving barrel but permitting relativeaxial movement therebetween.

A complete understanding of the invention may be ob- .tained from thefollowing detailed description and exing the notched contacting ends ofthe driving barrel and anvil;

Fig. 4 is an end elevation ;of one of said contacting ends;

Fig. 5 is a view similar to Fig. 1 showing. a modifica tion; I

Fig. 6 is an end elevation thereof; H Figs. 7 and 8 are views of themodified form conesponding to Figs. 3 and 4; and

Fig. 9 is a partial section through a modified form of the chuck in thedriven barrel.

Referring now in detail to the drawings and, for the present, to Figs.1-4, the device of my invention, indi cated generally at 10, comprises adriving barrel 11 having a shank 12 adapted to be inserted in the chuck13 of a portable drill of any conventional type, preferably providedwith a built-in driving motor. Barrel 11 has a bore 14 extending intothe end thereof opposite shank 12. The barrel 11 is rotatable in one endof a holding sleeve 15 having a handle 16. An anvil 17 in the form ofabored cylindrical block or plug is secured in sleeve 15 by a set screw18.

A driven barrel 19 rotatable in the other end of sleeve 15 has a shank20 extending rotatably and slidably through the bore in anvil 17. Barrel19 has a socket in ,the end opposite shank 20 for receiving the shank ofa Un SWSPMCMO ice rock drill 21 secured therein by a set screw 22. Shank20 has a flat 23 milled therein. A tapered set screw 24 in a radialtapped hole in barrel 11 has rotary driving engagement with shank 20 butis free from binding contact therewith when turned home, so as to allowrelative sliding movement between the shank and barrel 11 limited to thelength of the flat but sufficient to permit endwise engagement of thedriving barrel and anvil.

The contacting ends of the driving barrel 11 and anvil 17 have teeth ornotches 25 and 26, respectively, adapted to interfit, each tooth havingan inclined. cam portion terminating in a step whereby rotation of thebarrel relative to the anvil while their ends are yieldably held incontact by the force exerted on chuck 13 by the user, results in aseries of sharp blows being imparted to the anvil. These blows aretransmitted directly to driven barrel 19 and drill 21 since the normalforward pressure on handle 16 forces the anvil against the drivenbarrel. Drill 21 is thus caused to exert a highly effective drillingaction by a combination of rotation and percussion.

The attachment is ready for use upon the gripping of shank 12 in chuck13 and the securing of drill 21 in barrel 1 9. The portable drill isthen held by the usual handle in the users left hand while the rightgrips handle 16. When the drill motor is turned on, it drives shank 12in a clockwise direction looking forward from the motor end to the drillend, the barrel 11 drives shank 20 and the teeth of the barrel ride overthose of the anvil 17, causing repeated impact to be applied to thelatter by the force exerted by the users left hand.

.Figs. 58 show a modification which is similar in all respects to thedevice already described except for the shape of the teeth or notches 27and 28 and the details .of drill chuck 29 onthe driven barrel 30. Thischuck includes a frusto-conical portion 31 on the barrel, having aradial hole 32 therein, intersecting the axial socket for the shank ofdrill 33. A wedging pin 34 is fitted in hole 32. A sleeve 35 having aconical bore 36 is screwed on the outer end of barrel 30 which isthreaded to receive it. When the sleeve is turned home, it causes thepin to bind against the shank of the drill, holding it firmly in thesocket.

The inner end of sleeve 35 may be groovedas at 37 to form a finger gripand the outer end may be provided with flats 38 to afford a tool hold,to facilitate tightening and releasing the chucks grip on the drillshank.

The shape of teeth 27 and 28 as shown is such as to impart a lighttattoo or vibration to drill 33 as contrasted with the more intensivehammering caused by teeth 25 and 26.

Fig. 9 shows a modified form of barrel 30, designated 39, having aconical socket 40 to accommodate a tapered drill shank 41, and atransverse hole 42 for the usual knockout pin.

It will be apparent from the foregoing that the percussion attachment ofmy invention is very simple and therefore inexpensive to manufacture. Atthe same time, t

a driven barrel extending rotatably into the other end of said sleeve soas to make endwise contact with said plug, said driven barrel having ashank extending rotatably through the bore of said plug and into saiddriving gagg ng I 7 barrel, the adjacent ends of said driving barrel andanvil plug having i'nterfitti'n'g sets ofteeth, at least one set ofteeth having a sloping carniface adapted to contact the other set atteeth whereby, on relative. rotation between the driving barrel andanvil plug; the driving; barrel is' 5 moved axially away from theanvilplug, and means slida'hl'y but; non-rotatably relating, said shank.and said drivns ba L An-vattachment as defined by claim 1characterizedby saidmeanst including, a recess in said shank and a 10projection extending from the interior. of the driving barrel into saidrecess.

3. An attachment as defined by claim 2 characterize by said recess beinga Hat grilled in said shank and said projection being a radial screwthreaded into the driving barrel.

References Cited inther file of this patent v UNITED STATES PATENT S

